Navigation apparatus



y 1940. P. SORDOILLET 2,1 9,7 3

NAVIGATIQN APPARATUS I Filed May 27, 1938 2 Sheets-Sheet l Pzierre I fiardaz'ii w, )hz M M WMZW P. SORDOILLET 2.199.763

NAVIGATION APPARATUS May 7, 1940.

2 Sheets-She s; 2

Filed May 27, 1938 z swan-14 TIME 1 mai 9 illllllllllllllllzl 1/71 07 5, ",2 Pierre fa/dam Patented May 7, 1940 OFFICE fl Pierre Application Mayer, 1938, serial N6. 210,508

: m-rr ee June :1, 19ar' Q'CIaims. (01. 83-1) F rm invention relates its new oi celestial navigation and more particularly to apparatus and methods ioridentifying a celestial body and tionon or abovetheearthssuriaice; 1 ,v According tea ta ds anetnodyor ete n for determining thereirom, ,the observer's V posithegaltitude snefazi'm' th 'joi aLknoWniceleStial d uar '.ObServed;f andf tliefsidereal'jtinieloi the .10 prime: m idi n. ia i h wnf riihe m r u m chronor'neter o1the jve's sel, is noted; navigator then,"by dead reckoning; calc1 1lates the'esti mated altitude oi thecelestialbody observedand, by a standard method (for 1 exampleby' the 115 method or St. Hilaire) ailineioi position, or

Sumner line, is determined Thejvesselis then known 'to be atsome point thialine ofv position, and ii a second line of positionis established by means or a secon'dobservation made on a ditgo !erent celestial body,'.or a subsequent observation 4 fo'n' thesame celestiaibody, from a 'diiierent position,-'asfaiter the vessel has travelled a certain distance from the point where 'the iirst'observation was taken, theintersection oi the'twolines oi position, after correction vfor the travel oithe vessel between the times of the two observations. indicatesthe position of the vessel at thetime oi saidsecond observation; s

In order to establish a line of position "it'is v80 necessary first to identify the Celestial bodyjob- .served, and second, to calculate the'estimated altitude oi such body at the instant of observation, the estimated altitude being the altitude'at which the body would have been observed'ii the vessel had actually been at the position estimated by dead reckoning. Variousdevices have heretoiore been employed to assist the identificationof anobserved celestial body. One such device is described in United States Patent No. 1,401,448, 40 granted to Gilbert '1. Rude, and comprises a projection or diagram of the sky and a plurality of projections of the local sphere,'or earth, prepared for different latitudes, the latter projections being inscribed on transparent sheets. By selec'ting the terrestrial projection suitable for the observers estimated latitude, and orienting it with respect to the celestial projection in the manner described in said patent, it is possible to identify any observed celestial body which is so inscribed on the celestial projection. However. this and similar, devices. while of assistance in identiiying celestial bodies, are of no use in connection with the subsequent operations-necessary to determine the position of the vessel. as It isan object of the present invention to provide ani apparatus which'is adapted notonly to enablefthe'naivigatorto'readily identify an observedcel'estial body, but also to read directly its .estimated'altitude', thereby enabling him, without any calculation except that of his dead reck- 5 -o'n'i'ng positionjorestimated-latitude, to determine Anj'the'rf bi t i the present invention is the 'provision cifa"method for determining aline of position without the'use oi. any calculation except thatfoi the .dead reckoning position.

' A furtherobj ect oi the present invention is the provision goi anapparatus oi the type mentioned in .which' the necessary stereographic projections are made on a very fine scale, by photographic reproductionor otherwise, so as to be of a size permitting theirconvenient manipulation, to-

" gether with optical means by which the estimated alti'tudeoi ;an observed" celestial body may be easilyand accurately determined from such pro- 20 l mons. 1

iurtherobject is'the provision of an apparatus of thetype mentioned, including a microscope having a scale arranged in the focal plane of the eyepiecegwherebysaid scale may be inter- 25 calated between adjacent altitude circles of the terrestrial projection, whereby the estimated altitude of an observed celestial body may be directly read in degrees'and minutes.

Another object is v the provision of an apparatus 30 f of the typeme'ntioned, in which the necessary manipulation of the ster'eographic projections is eiiectedmechanically, the extentoi such manipulation beingsimultaneously registered by means .0! registering devices of the odometer type, so 5 that the possibilityoferror is substantially eliminated. 7

Other and further objects, ieatures and advantages of the present invention will be apparent to those skilled in the art upon a consideration of iii the following specification and accompanying drawings, in which Figure-1 is a diagram illustrating the manner of making the stereographic projections ern ployed'in accordance withthe present invention;

Figure 2 is a plan view of an apparatus con structed in accordance with the present invention, a portion or the casing being broken away to reveal theoperating mechanism within; m

Figure 3-isa vertical section on line 3-3 a? Figure 2; j I

-Figura 4 is a diagrammatic view illustrating the registering mechanism comprised in the appsratus of Figure 2; rm

line 5-5 of Figure 4; and

Figure 6 is an elevation 01' the apparatus 01 Figure 2 in combination with a microscope oiv th type hereinafter described. I

Inaccordance with the method of the present invention a stereographic projection 01 the celestial sphere and a stereographic projection of the terrestrial sphere faregsuperposed, and are then adjusted relatively asai'unction oi the sidereal time'oi the primemeridian and of the estimated longitude of the navigators position, which en-.

ables identification of an observed heavenly body by means of coordinates inscribed on the terrestrial projection. At the same time, by means' to be described, the estimated altitude oi the ob! served body may be accurately read, and the, line 01' position of the vessel determined without further calculation. The position of bodies in the celestial sphere (referring particularly to those which are commonly used in navigating, and are referred to as f'fnavigating stars) is usually defined by. meansot their horary coordinates, or right ascension and declination. The ri ht ascension is the angle comprisedbetween the semi-major circle or celestial through the first point of Aries and that on which thebody or star is located. 'lhe declination of a star is the distance from the star to the celestial equator measured on the circle 01' declination, that is, the great circle which passes through thestar and through the poles oithe celestial sphere.

The variation of the right and declination oi the navigating stars with time depends upon several factors, among which the precession is by far the most important. The

. precession is the movement by which the axis of the earth slowly describes a cone.

The annular variation 0! the right ascension and the declination is in accordance with the formulas I A RA=m--n sin RA turd.

and

A d=n cos RA,

in which the value of n is approximately 20" and the value of m is approximately 46". It will be seen therefore, thatthese coordinates do not vary by more than one minute in the course of a year. Thus, one and the same projection of the celestial sphere can serve for at least a year, and even several years, it the navigating stars which are inscribed thereon are judiciously chosen. Such projections of ,the celestial sphere are well known, and need not be further described. In accordance with the present invention, two such projections are employed. one for the northern hemisphere and one for the southern hernisphere.

The present invention employs a plurality of stereographic projections of the earth's surface, made according to diiierent latitudes, such projections being taken on a plane parallel to that of the Equator. Each such projection will consist of a series of arcs designating azimuths and a series of circles or arcs'ting altitudes. such projections being the same for all points on a given latitude, regardless of longitude. In accordance with the present invention, the .projections of the celestial and terrestrial spheres are superposed and relatively rotated asa iunotion'of the sidereal time of, the p ime meridian and the estimated longitude of the navigators position, the rotation being effected about a point common to the projections and corresponding to the axis of the poles. The extent of rotation corresponds to the algebraic sum .of the sidereal time of the first meridian and the estimated longitude oi the place. This rela tive rotation 01' the two projections. represents or compensates for the-navigators-displacement in longitude from the primemeridian. and for the earth's rotation in respect to the stars, or in other words, the sidereal time of the prime meridian. With the two projections thus oriented relative, to each other, the local coordinates.

- (altitude and-azimuth) oi an observed body can be directly read from the terrestrial projection. C0nversely,1ii an unknown star has been observed at a given altitude, and in a given azimuthat a particular moment of time, by orienting the two projections in the manner indicated,

the observed body can be easily identifled bymeans of the coordinates inscribed on the terrestrial projection. I

The terrestrial projection for any given latitude is divided into two portions representing,

respectively. that portion of the local hemisphere above the Equator and that portion falling below the Equator. The local hemisphere is defined. for present; purposes, as that portion of the.

earth's suriace lying on the observer's side of a great circle lying in a plane parallel-to that of the observer's horizon, in other words, the local hemisphere may be defined as that hemisphere pole, 'or position or the observer, is at point O on the terrestrial sphere NOS, the letters N and projecting on the plane P1, which'isIparallei to the equator oi the sphere NOS, those points lying above the equator, the center of projection is the south pole S. The line A-B represents, thus, a projection of the observer's meridian, and the circle ABCD aprojection of the equator abcd; The point Z is a projection of the observer's position or pole 0 oi the local hemisphere, while the arc CFD is a projection 40 8 representing the north and south poles. For

of the portion cfd of the observer's equator cfde lying above the earth's Equator abcd. The aziequator. The area between CED and C81) theretore represents that portion or the local hemisphere lying below the earths equator.

To inscribe the azimuth arcs and altitude arcs and circles on the plates P1 and P, the following methods are employed: The altitudes are represented by circles or arcs having their centers on .the line A-B representing the local meridian.

the distance a: from the center of projection N to the center of a given altitude circle or are being given by the formula:

cotan g -j-tan E 2 wherein h=altitude and L=latitude oi the place.

The radius of a given azimuth arc is deter- 16 mined by the formula:

1 cos L sin Z in which L=latitude of the place and Z=azi- The appearance of a pair of stereographic projections of a local hemisphere, constructed as just described, is illustrated in Figure 2.

Projections constructed as described may be m: employed in the method as described and claimed herein, regardless of the apparatus with which they may be used, but a particularly suitable apparatus for this purpose is illustrated in Figures -26, and will now be described.

In order to facilitate an understanding of the invention, reference is made to the embodiment thereof shown in the accompanying drawings and detailed descriptive language is employed. It will nevertheless be understood that no' limitation of 301 the invention is thereby intended and that various changes and alterations are contemplated such as would ordinarily occur to one skilled in the art to which the invention relates.

Referring to Figures 2 and 3, the apparatus 3;. comprises a suitable casing K in which is mounted a transparent plate I on which is inscribed a stereographic projection of the local hemisphere, the northern portion being shown on the left and the southern portion on the right. A second transparent plate 2 carries a stereographic projection of the northern celestial hemisphere,

and is mounted in a ring 4 suitably journalled in the casing K immediately below the left hand portion of the plate I. Another transparent plate 3 carries a stereographic projection of the southern celestial hemisphere, and is mounted in a ring 5 which'is likewise journalled in the casing K immediately below, the right'hand portion of the plate I. The rings 4 and 5 are provided with peripheral teeth 6, 6 meshing with the threaded portion I of a shaft 8 journalled in the casing K and extending rearwardly between the rings 4 and 5. The outer end of the shaft 8 is fitted with a knurled button 9, while its inner end is provided with abevel gear I0, secured thereon or formed integrally therewith. The bevel gear I0 meshes with a bevel pinion H which is free to turn upon a. sleeve I2, the latter. being in turn journalled upon a transverse fixed shaft I3. The 0, bevel pinion II is provided with a peripheral flange I4 carrying oppositely disposed stub shafts I5, I on which are journalled planetary gears I6, l6. Each of the latter meshes with a sun gear I1, integral with the sleeve I2, and an orbit 5 gear I8 secured upon or integral with a sleeve I9 which is journalled on the shaft I3.

A brake element 20, corresponding in diameterand general configuration to the orbit gear I8, is secured upon or formed integrally with the sleeve 70 I2. A brake shoe 2| is supported between the brake element and the orbit gear I8, for alternative engagement therewith, by a lever 22 pivoted as at 23 and provided with a handle portion 24. It will be obvious that by moving the 75v brake shoe 2| into the position illustrated in Figure 4, that is, into engagement with the brake element 20, the sleeve I2 is locked while the sleeve I9 is free to rotate in accordance with the movements of the shaft 8' and associated mechanism. Alternatively, by moving the brake shoe 2| in the opposite direction, into engagement with theorbit gear I8, the sleeve I9 will be held against rotation while the sleeve I2 will be free to turn in accordance with the movements of the shaft 8.

A drum 25 is secured upon or formed integrally with the sleeve I9 and carries a series of numerals representing seconds of time, preferably at intervals of four seconds, as for example, 0,, 4, 8, etc., up to 56. A second drum 25 is journalled on the sleeve I9 adjacent the drum 25 and indicating units of minutes of time. The drum 26 is adapted to be driven from the drum 25 at 5 the speed of the latter, the arrangement of interengaging elements by which this result is accomplished being well known. A drum 21, adapted to be driven from the drum 26, carries numerals from 0 to 5, inclusive, indicating tens of minutes, and is arranged to be driven at of the speed of the drum 26. In a similar manner, drums 28 and 29 are marked and arranged to indicate units of hours and tens of hours of time, the figures on the several drums being visible through appropriate windows 38, 30, 30" in the casing K (Fig. 2). The registering device just described is adapted to register the sidereal time of the prime meridian, as indicated by an appropriate legend inscribed on the casing adjacent the windows 30, etc.

Similarly, the sleeve I2 is provided with a group of drums 3| to 35, inclusive, adapted to register degrees and minutes of east longitude, and a similar group of drums 38 to 40, inclusive, adapted to register west longitude in degrees and minutes, such drums being 'visible through the windows 4|, 4| and 42, 42, respectively. The numerals on the two groups of drums are arranged so that as the figures indicated by one group of drums increase in value, those indicated by the other group decrease correspondingly, bothgr'oups being adapted to register zero simultaneously.

It will be apparent that by reason of the described mechanism, the transparent plates 2 and 3,'carrying the projections of the northern and southern celestial hemispheres, may be rotated with respect to the plate I, which carries a. stereographic projection of the local hemisphere corresponding to the navigators estimated position, by turning the button 9, while at the same time the desired registering device is actuated through the planetary gearing, toregister the sidereal time of the prime meridian, or alternatively the'longitude (east or west as the case may be) corresponding to the rotation of the plates 2 and 3. In order to avoid play or back lash, the rings 4 and 5 are preferably biased towards zero or starting position by suitable resilient means, not shown.

In using the apparatus, the navigator concen- 'trates his attention upon the plate 2 and the left hand portion of the plate I if the observed star is in the northern hemisphere, and upon the plate 3 and the right hand portion of plate I if the star is in the southern hemisphere. The apparatus isintended to be employed in the following manner. I

Let it be assumed, for example, that the posi tion of the vessel, as estimated by the navigator, is latitude 45 30" north and longitude 15 34" east, and that at 11 hours 35 minutes 24 seconds oclock on his sidereal time clock the navigator has observed a star of the first magnitude at 35 altitude and azimuth 185. He wishes to determine the value of He-Ho (the difference between the estimated altitude and the observed altitude of the particular star observed), which will enable him to enter on his chart the line of position or Sumner line. Assuming that the plate I, which is of course interchangeable with other similar plates, carries the appropriate projection for the estimated position, the navigator moves the handle 24 so as to bring the brake shoe 2| into engagement with the brake element 20, thus locking the sleeve 12, and then turns the button 9 until the figures appearing in the windows 30, 30 indicate 11 hours, minutes, 24 seconds of sidereal time. The position of the brake shoe 2| is then reversed, locking-the sleeve 19, and the button 9 turned in the opposite direction until the figures 15 34" appear in the windows labelled east longitude. It will be seen that the rings 4 and 5, carrying the plates 2 and 3, have thus been rotated in accordance with the algebraic sum of the sidereal time of the prime meridian and the estimated longitude of the place, east longitude being regarded as minus and west longitude as plus. When this operation has been completed, the coordinates inscribed on the transparent plate 5 will indicate the star which has been observed, and which is identified by its name inscribed on plate 3. Thus, in the example which has just been described, the star S, inscribed on plate 3, will be located approximately at altitude 35 and azimuth 185 as inscribed on plate I. The navigator is thus able to identify the observed star. It then only remains for him to ascertain the exact estimated altitude (He) oi the star S in order to be able to fix his line of position.

In order to enable the reading of degrees and minutes from the plate I with sufflcient accuracy, the apparatus thus far described is preferably associated in a fixed position with a. microscope now to be described. Thus, in Figure 6, the apparatus described above, and indicated at K, is secured fixedly upon the standard supporting a microscope 5|. The latter is provided with two lenses 52 and 53, one having a magnification of about ten diameters, permitting reading directly the position of a star S, in degrees, on the system of lines carried by the plate I. In the example given, the altitude He lies between 35 and 36. The microscope being centered on the star S, the navigator changes the lens to pass to a magnification of between 50 and 100 diameters. He then completes regulation of the magnification with the aid of an adjusting knob 54 so that a minute scale, arranged in the eyepiece and comprising divisions, is exactly intercalated between the altitude circles 35" and 36". He is then enabled to read directly the estimated altitude of the star S in degrees and minutes.

The microscope 5! is supported by an arm 55 which is slldably mounted in a post 56, the latter in turn being slidably mounted in the standard 50, the slides 55 and 56 being secured, after ad-' justment, by means of set screws 51 and 58 respectively. The microscope 5| can thus, ina well known manner, be centered over any portion oi. the plate I.

By reason of the provision of a microscope of the nature described, it is possible to employ projectlons which are greatly reduced in size, so as to be suitable for employment in an apparatus according to the present invention. The advantage of this feature will be'obvious when it is considered that in order to be easily read by the naked eye, the minute divisions of such a projectlon should be spaced at least a millimeter apart, which would requke a projection exceeding seven meters in diameter.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. Navigating apparatus comprising a member having a stereographic projection of the sky inscribed thereon, a second member having a stereographic projection of the local hemisphere inscribed thereon, including a system oi altitude and azimuth coordinates, said members being superposed and one of said members being mounted for rotation about a point common to said projections and corresponding to the axis of the poles, said upper member being of transparent material, and means for effecting rotation of said rotatable member in accordance with the algebraic sum 01' the sidereal time of the prime meridian and the estimated longitude of the observer, said last means comprising a manually rotatable shaft, gearing connecting said shaft and said rotatable member, means for registering the extent of rotation of said rotatable member, and gearing connecting said shaft and said registering means.

2. Navigating apparatus comprising a ilxed member carrying a stereographic projection of the local hemisphere, including azimuth and altitude coordinates, a rotatable member carrying a stereographic projection of the sky, said members being superposed, means m rotating said second member about a point common to said projections and corresponding to the axis of the poles, and means for simultaneously registering the extent of rotation in terms of the sidereal time of the prime meridian and the estimated longitude of the observer.

3. Navigating apparatus comprising a fixed member carrying a stereographic projection of .the local hemisphere, including azimuth and altitude coordinates, a rotatable member carrying a stereographic projection of the slgv, said members being superposed, means for rotating said second member about a point common to said projections and corresponding to the axis of the poles, and means for simultaneously registering the extent of rotation in terms of the sidereal time of the prime meridian and the estimated longitude of the observer, said last means comprising registering devices of the odometer type having suitable figures inscribed thereon and operatively connected to said rotatable member.

4%. Navigating apparatus comprising a iixed member carrying a stereographic projection of the local hemisphere including azimuth and altitude coordinates, the portions of said hemisphere lying above and below the equator, respectively, being separately depicted, a pair of rotatable members carrying, respectively, stereographic 5. Navigating apparatus comprising a fixed member carrying a stereographic projection of the local hemisphere including azimuth and altitude coordinates, the portions of said hemisphere lying above and below the equator, respectively, being separately depicted, a pair of rotatable members carrying, respectively, stereographic projections of the northern celestial hemisphere and the southern celestial hemisphere, said rotatable members being supported for rotation about the poles of their respective projections, said poles being in register with the corresponding poles of said projection carried by said fixed member, means for simultaneously actuating said rotatable members and comprising a manually rotatable shaft operatively connected to said members, and means for simultaneously regis-,

tering the extent of rotation of said rotatable members, said registering means being operatively connected with said shaft.

6. Apparatus as defined in claiml, said reg,- istering means comprising devices of the odometer type, one of said devices being graduated in hours, minutes and seconds and another of said devices being graduated in degrees and minutes of longitude.

'1. Apparatus as defined in claim 1, said registering means comprising devices of the odometer type, one of said devices being graduated in hours, minutes'and seconds and another of said devices being graduated in degrees and minutes of longitude, said registering devices being operatively connected to said shaft by means of a selective planetary gear train whereby said devices may be alternatively operated in accordance with the movements of said rotatable memher.

8. Apparatus as defined in claim 5, said reg-' istering means comprising devices of the odometer type, one of said devices being graduated in hours, minutes and seconds and another of said devices being graduated in degrees and minutes of longitude.

9. Apparatus as defined in claim 5, said registering means comprising devices of the odometer type, one of said devices being graduated in hours, minutes and seconds-and another of said devices being graduated in degrees and minutes of longitude, said registeringdevices being operatively connected to said shaft by means of a selective planetary gear train whereby said devices may be alternatively operated inaccordance with the movements of said rotatable member. I

PIERRE SORDOILLE'I. 

